<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>basic_datagram_socket::async_wait</title>
    <link rel="stylesheet" href="../../../boostbook.css" type="text/css">
    <meta name="generator" content="DocBook XSL Stylesheets V1.75.2">
    <link rel="home" href="../../../index.html" title="Asio">
    <link rel="up" href="../basic_datagram_socket.html" title="basic_datagram_socket">
    <link rel="prev" href="async_send_to/overload2.html"
          title="basic_datagram_socket::async_send_to (2 of 2 overloads)">
    <link rel="next" href="at_mark.html" title="basic_datagram_socket::at_mark">
</head>
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
<table cellpadding="2" width="100%">
    <tr>
        <td valign="top"><img alt="asio C++ library" width="250" height="60" src="../../../asio.png"></td>
    </tr>
</table>
<hr>
<div class="spirit-nav">
    <a accesskey="p" href="async_send_to/overload2.html"><img src="../../../prev.png" alt="Prev"></a><a accesskey="u"
                                                                                                        href="../basic_datagram_socket.html"><img
        src="../../../up.png" alt="Up"></a><a accesskey="h" href="../../../index.html"><img src="../../../home.png"
                                                                                            alt="Home"></a><a
        accesskey="n" href="at_mark.html"><img src="../../../next.png" alt="Next"></a>
</div>
<div class="section">
    <div class="titlepage">
        <div>
            <div><h4 class="title">
                <a name="asio.reference.basic_datagram_socket.async_wait"></a><a class="link" href="async_wait.html"
                                                                                 title="basic_datagram_socket::async_wait">basic_datagram_socket::async_wait</a>
            </h4></div>
        </div>
    </div>
    <p>
        <span class="emphasis"><em>Inherited from basic_socket.</em></span>
    </p>
    <p>
        <a class="indexterm" name="asio.indexterm.basic_datagram_socket.async_wait"></a>
        Asynchronously
        wait for the socket to become ready to read, ready to write, or to have
        pending error conditions.
    </p>
    <pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span>
    <span class="keyword">typename</span> <a class="link" href="../WaitToken.html" title="Wait token requirements">WaitToken</a> <span
                class="special">=</span> <a class="link"
                                            href="../asynchronous_operations.html#asio.reference.asynchronous_operations.default_completion_tokens"><span
                class="emphasis"><em>DEFAULT</em></span></a><span class="special">&gt;</span>
<a class="link"
   href="../asynchronous_operations.html#asio.reference.asynchronous_operations.automatic_deduction_of_initiating_function_return_type"><span
        class="emphasis"><em>DEDUCED</em></span></a> <span class="identifier">async_wait</span><span
                class="special">(</span>
    <span class="identifier">wait_type</span> <span class="identifier">w</span><span class="special">,</span>
    <span class="identifier">WaitToken</span> <span class="special">&amp;&amp;</span> <span
                class="identifier">token</span> <span class="special">=</span> <a class="link"
                                                                                  href="../asynchronous_operations.html#asio.reference.asynchronous_operations.default_completion_tokens"><span
                class="emphasis"><em>DEFAULT</em></span></a><span class="special">);</span>
</pre>
    <p>
        This function is used to perform an asynchronous wait for a socket to enter
        a ready to read, write or error condition state. It is an initiating function
        for an <a class="link" href="../../overview/model/async_ops.html" title="Asynchronous Operations">asynchronous
        operation</a>,
        and always returns immediately.
    </p>
    <h6>
        <a name="asio.reference.basic_datagram_socket.async_wait.h0"></a>
        <span><a name="asio.reference.basic_datagram_socket.async_wait.parameters"></a></span><a class="link"
                                                                                                 href="async_wait.html#asio.reference.basic_datagram_socket.async_wait.parameters">Parameters</a>
    </h6>
    <div class="variablelist">
        <p class="title"><b></b></p>
        <dl>
            <dt><span class="term">w</span></dt>
            <dd><p>
                Specifies the desired socket state.
            </p></dd>
            <dt><span class="term">token</span></dt>
            <dd>
                <p>
                    The <a class="link" href="../../overview/model/completion_tokens.html" title="Completion Tokens">completion
                    token</a> that will be used to produce a completion handler, which
                    will be called when the wait completes. Potential completion tokens
                    include <a class="link" href="../use_future.html" title="use_future"><code
                        class="computeroutput"><span class="identifier">use_future</span></code></a>,
                    <a class="link" href="../use_awaitable.html" title="use_awaitable"><code
                            class="computeroutput"><span class="identifier">use_awaitable</span></code></a>,
                    <a class="link" href="../yield_context.html" title="yield_context"><code
                            class="computeroutput"><span class="identifier">yield_context</span></code></a>,
                    or a function object with the correct completion signature. The function
                    signature of the completion handler must be:
                </p>
                <pre class="programlisting"><span class="keyword">void</span> <span
                        class="identifier">handler</span><span class="special">(</span>
  <span class="keyword">const</span> <span class="identifier">asio</span><span class="special">::</span><span
                            class="identifier">error_code</span><span class="special">&amp;</span> <span
                            class="identifier">error</span> <span class="comment">// Result of operation.</span>
<span class="special">);</span>
</pre>
                <p>
                    Regardless of whether the asynchronous operation completes immediately
                    or not, the completion handler will not be invoked from within this
                    function. On immediate completion, invocation of the handler will
                    be performed in a manner equivalent to using <a class="link" href="../post.html" title="post"><code
                        class="computeroutput"><span class="identifier">post</span></code></a>.
                </p>
            </dd>
        </dl>
    </div>
    <h6>
        <a name="asio.reference.basic_datagram_socket.async_wait.h1"></a>
        <span><a name="asio.reference.basic_datagram_socket.async_wait.completion_signature"></a></span><a class="link"
                                                                                                           href="async_wait.html#asio.reference.basic_datagram_socket.async_wait.completion_signature">Completion
        Signature</a>
    </h6>
    <pre class="programlisting"><span class="keyword">void</span><span class="special">(</span><span class="identifier">asio</span><span
            class="special">::</span><span class="identifier">error_code</span><span class="special">)</span>
</pre>
    <h6>
        <a name="asio.reference.basic_datagram_socket.async_wait.h2"></a>
        <span><a name="asio.reference.basic_datagram_socket.async_wait.example"></a></span><a class="link"
                                                                                              href="async_wait.html#asio.reference.basic_datagram_socket.async_wait.example">Example</a>
    </h6>
    <pre class="programlisting"><span class="keyword">void</span> <span class="identifier">wait_handler</span><span
            class="special">(</span><span class="keyword">const</span> <span class="identifier">asio</span><span
            class="special">::</span><span class="identifier">error_code</span><span class="special">&amp;</span> <span
            class="identifier">error</span><span class="special">)</span>
<span class="special">{</span>
  <span class="keyword">if</span> <span class="special">(!</span><span class="identifier">error</span><span
                class="special">)</span>
  <span class="special">{</span>
    <span class="comment">// Wait succeeded.</span>
  <span class="special">}</span>
<span class="special">}</span>

<span class="special">...</span>

<span class="identifier">asio</span><span class="special">::</span><span class="identifier">ip</span><span
                class="special">::</span><span class="identifier">tcp</span><span class="special">::</span><span
                class="identifier">socket</span> <span class="identifier">socket</span><span
                class="special">(</span><span class="identifier">my_context</span><span class="special">);</span>
<span class="special">...</span>
<span class="identifier">socket</span><span class="special">.</span><span class="identifier">async_wait</span><span
                class="special">(</span><span class="identifier">asio</span><span class="special">::</span><span
                class="identifier">ip</span><span class="special">::</span><span class="identifier">tcp</span><span
                class="special">::</span><span class="identifier">socket</span><span class="special">::</span><span
                class="identifier">wait_read</span><span class="special">,</span> <span
                class="identifier">wait_handler</span><span class="special">);</span>
</pre>
    <h6>
        <a name="asio.reference.basic_datagram_socket.async_wait.h3"></a>
        <span><a name="asio.reference.basic_datagram_socket.async_wait.per_operation_cancellation"></a></span><a
            class="link"
            href="async_wait.html#asio.reference.basic_datagram_socket.async_wait.per_operation_cancellation">Per-Operation
        Cancellation</a>
    </h6>
    <p>
        On POSIX or Windows operating systems, this asynchronous operation supports
        cancellation for the following <a class="link" href="../cancellation_type.html" title="cancellation_type"><code
            class="computeroutput"><span class="identifier">cancellation_type</span></code></a> values:
    </p>
    <div class="itemizedlist">
        <ul class="itemizedlist" type="disc">
            <li class="listitem">
                <code class="computeroutput"><span class="identifier">cancellation_type</span><span
                        class="special">::</span><span class="identifier">terminal</span></code>
            </li>
            <li class="listitem">
                <code class="computeroutput"><span class="identifier">cancellation_type</span><span
                        class="special">::</span><span class="identifier">partial</span></code>
            </li>
            <li class="listitem">
                <code class="computeroutput"><span class="identifier">cancellation_type</span><span
                        class="special">::</span><span class="identifier">total</span></code>
            </li>
        </ul>
    </div>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%">
    <tr>
        <td align="left"></td>
        <td align="right">
            <div class="copyright-footer">Copyright © 2003-2022 Christopher M. Kohlhoff<p>
                Distributed under the Boost Software License, Version 1.0. (See accompanying
                file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
            </p>
            </div>
        </td>
    </tr>
</table>
<hr>
<div class="spirit-nav">
    <a accesskey="p" href="async_send_to/overload2.html"><img src="../../../prev.png" alt="Prev"></a><a accesskey="u"
                                                                                                        href="../basic_datagram_socket.html"><img
        src="../../../up.png" alt="Up"></a><a accesskey="h" href="../../../index.html"><img src="../../../home.png"
                                                                                            alt="Home"></a><a
        accesskey="n" href="at_mark.html"><img src="../../../next.png" alt="Next"></a>
</div>
</body>
</html>
